Postop Radiation Extends Survival in Endometrial Cancer

Action Points

Explain to patients who ask that this study reveals a statistical association between adjuvant radiotherapy and survival; however, these data do not prove a causal relationship as this was an observational study that was not randomized.

SALT LAKE CITY, Jan. 24 - Adjuvant radiation therapy for endometrial cancer can save lives, and the benefit is consistent irrespective of age, according to a large population analysis.

The retrospective analysis of data culled from 21,249 women treated for endometrial cancer from 1988 through 2001 found survival was significantly better for women with grade 1 and grades 3 and 4 disease (P<0.001 for both), and was reported in the Jan. 25 issue of the Journal of the American Medical Association.

The study is believed to the largest population analysis of endometrial cancer, reported Christopher M. Lee, M.D., of the University of Utah and colleagues. The results revealed an association in both overall survival and relative survival.

The researchers identified endometrial cancer patients using data from the Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute. All women had stage IA-C, node-negative endometrial adenocarcinoma.

Of the total population, 4,080 received adjuvant radiation therapy. Stage IC/grade 1 and stage IC/grades 3 and 4 cohorts were found to have statistically significant improvements in overall survival with the addition of adjuvant radiotherapy (both P<.001).

Among the findings:

For women with grade 1 disease younger than 56, radiation therapy was associated with a 98% five-year survival versus 88% for women who did not receive radiation therapy. The corresponding survival rates for women ages 56 to 75 were 94% versus 85%, and for women over age 75 the rates were 84% and 67%.

For women with grades 3 and 4 disease the survival rate for women younger than 56 who received adjuvant radiation therapy was 86%, versus 77% for those who were not given post-operative radiation. Survival for women ages 56 to 75 who received radiation was 66% versus 56%, and for women older than 75 the rates were 53% vs.39%.

In both groups radiation was associated with better survival at 10 years as well. It was 92% versus 69% for women younger than 56 with grade 1 disease, and 86% versus 77% for the youngest women with grade 3 and 4 disease.

Troy Scroggins, M.D., who chairs radiation oncology at the Ochsner Clinic, said the findings are significant because there has been an ongoing debate about "what we should really be doing with patients who have stage 1 disease, and this is important because the majority of patients that we see have stage 1 disease."

Dr. Scroggins, who was not involved in the study, said that "in clinical practice, most of us are going to use radiation with these patients because we have known that we have a better outcome with radiation. But what wasn't known was whether this treatment could extend survival."

This study, Dr. Scroggins said, gives radiation oncologists "more ammunition to back up the recommendation for radiation therapy."

The study however cannot determine causality for the association between radiation and survival benefit. This is because, as pointed out by the authors, it was limited by its observational design, the lack of randomization, and by the lack of specific clinical and pathological data that are known to be prognostic. Moreover, the authors pointed out that while there is a 97.5% ascertainment at participating SEER centers that are the source of the data, those centers represent only 10% of the U.S. population.

The authors also cautioned that a statistical analysis is no substitute for clinical judgment.

Finally, they concluded, it is to be hoped that "appropriate adjuvant [radiation therapy] will be used to decrease the death rate from this most common of gynecological malignancies."

Reviewed by Zalman S. Agus, MD Emeritus Professor University of Pennsylvania School of Medicine

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